When my brother was getting married, I knew he was going to be short on money towards his honeymoon so I offered to pay for it, and that was my gift to them.
But looking back to when I got married, I have to agree that cash is the best gift. Not saying the appliances or other things aren't great and all... But cash gives the couple liberty to use it towards the things they really need, or want.
BOL to your brother!